Biodiversity and climate change

Global warming is an emerging threat to biodiversity around the world. As temperatures rise, the geographic location of climatic envelopes will shift significantly, forcing species to migrate. Those that are not able to keep up with their respective climatic envelopes may become extinct.

Background

Biological diversity allows myriad species to work together to maintain the environment without costly human intervention. Thus, biodiversity is an irreplaceable natural resource crucial to human well-being. Habitat destruction, pollution, invasive species, overexploitation, and global climate change have led to an accelerated decline in biodiversity in recent decades. As a result, the current rate of species extinctions is estimated at one hundred to one thousand times greater than the natural rate. If the biodiversity decline is not slowed, Earth will be much less inhabitable for future generations. As a result, future research must focus on developing a strong understanding of the biological mechanisms that mediate responses to climatic and anthropogenic changes in the environment.

Past and Current Extinctions

There is no doubt that climate plays a central role in fluctuations in biodiversity. At least four out of five recognized mass extinction events on Earth are attributable to climate change. The Triassic event (around 200 million years ago) was triggered by atmospheric carbon dioxide (CO₂) levels increasing to one hundred times the current level. The Permian-Triassic extinction (about 251 million years ago), the greatest mass extinction on record, resulted from global temperature rises to between 10 and 30 degrees Celsius higher than today’s average temperature. That single event is believed to have wiped out 95 percent of the life in Earth’s oceans and nearly 75 percent of terrestrial species.

Climate change has also led to the emergence of new species. In fact, some experts believe that rapid climate changes in Africa might have created suitable conditions for the emergence of modern humans. In particular, rapid changes in water sources are believed to have forced primitive hominids rapidly to change and adapt. Under this theory, Homo sapiens evolved from its progenitor species as a result of these changes. In general, however, the birth of new species following a mass extinction usually takes millions of years. Recovery from severe losses of biodiversity does not occur on a human timescale.

Many experts believe that Earth is currently in the midst of a sixth mass extinction event. Although there are many debates raging over the extent of the current biodiversity loss, very few scientists dispute the fact that species extinction is occurring as a result of climate change and human activities. Comprehensive studies conclude that 15 to 37 percent of Earth’s species will become extinct by 2050 as a result of projected climate changes. Such massive extinctions will wreak havoc on ecosystems around the world.

Impact of Climate Change on Biodiversity

Climate change can affect species in a number of ways. These include the expansion, contraction, and shift of habitats; changes in temperature, precipitation, and other environmental conditions; increased frequency of diseases; the emergence of invasive species; and disrupted ecological relationships. With a rising temperature, extreme and severe weather events will become more frequent, including extreme high temperatures, very severe storms, large floods, a decrease in snow cover and ice caps, rising sea levels, and alteration to the distribution of infectious diseases and invasive species.

As temperatures rise, habitats for many plants and animals will be altered, eliminating the homes and niches to which they have adapted. It is estimated that up to 60 percent of northern latitude habitats could be affected by global warming. In response to global warming, plants and animals will migrate to more suitable climes. Specific effects have already been observed. The tree line near Olympic National Park has moved up in altitude by more than 30 meters since the 1980s. The red fox is spreading northward in Australia in response to the warming climate. Many fish species along the Pacific coast are shifting their habitats northward in search of cooler waters.

Biodiversity Loss Due to Human Activities

Before the rapid explosion of human populations, many species may have responded to climate change by migrating northward or southward to the cooler regions. Contemporary human activities such as urbanization, road construction, agriculture, and tourism have fragmented, converted, and destroyed many habitats and potential migration routes and thus make it much more difficult for species to migrate. As a result, many species struggle to cope with climate change as they decline in population, often facing outright extinction.

The replacement of low-intensity farming systems with industrial agroecosystems has led to a significant decline in biodiversity. For example, the deforestation of tropical rainforests represents an alarming threat to biodiversity. In some regions, forest cover remains high, but intensive management has turned natural forests into stands of very few or single tree species, leading to the loss of many animal species as well. The disappearance of wetlands worldwide has been dramatic over the last century, ranging from 60 percent in China to 90 percent in Bulgaria. The living planet index declined by 37 percent between 1970 and 2000.

Context

The loss of biodiversity is both real and accelerating, as Earth continues to warm. According to the World Wildlife Fund's Living Planet Report 2022, conservation efforts launched in the 1970s have done little to slow the decline of biodiversity and mitigate human damage to the global ecosystem. The report found that, between 1970 and 2022, monitored wildlife populations declined by 69 percent. Freshwater species experienced the greatest loss, seeing an 83 percent decline in population. Marine and terrestrial species populations both declined by more than 35 percent. Species population and biodiversity decline were greatest in Latin America and the Caribbean—a region rich in rainforest ecosystems—where species populations declined by an average of around 94 percent.

The irreversible loss of biodiversity poses serious threats to the well-being of present and future generations. The societal response to this threat has been slow, stemming from a lack of awareness of the vital role biodiversity plays. The key to the solution is education. In the early twenty-first century, efforts to demand change from policymakers and business leaders have grown. Significant protests have taken place in some places, such as the large June 2024 march in London, in which thousands of people and 350 environmental groups came together to protest the lack of action by United Kingdom leaders to protect the loss of wildlife in that region.

There is often a perception of conflict between the need to preserve biodiversity and the goal of economic development. Policymakers and businesses will need to work together to encourage and reward economic development that is friendly to biodiversity. Biodiversity is more complex than many other environmental concerns because it involves several levels of biological organization, including genes, individuals, species, populations, and ecosystems. It cannot easily be measured by a single indicator, such as temperature or rainfall. Nevertheless, countries can work together to build consensus and achievable goals aiming at slowing down the biodiversity decline or even restoring habitats for the recovery of threatened species. In late 2022, leaders from close to two hundred nations gathered at the United Nations Biodiversity Conference, also called COP15, where they adopted a global biodiversity framework that provided a plan for the conservation and management of biodiversity over the following decade. Among the major points of the agreement was a plan to restore 30 percent of the earth's damaged ecosystems by 2030. Similarly, in 2020 the European Union (EU) issued a new directive, called the EU Biodiversity Strategy to 2030, that proposed several targets to restore and protect habitat loss and endangered species in that region.

Key Concepts

• biodiversity: the total variation within and among all species of life in a given area, ecosystem, or context
• climatic envelope: the range of temperatures, precipitation, and other climatic parameters to which a species has adapted
• living planet index (LPI): a number representing the population sizes of vertebrate species representative of terrestrial, freshwater, and marine ecosystems around the world; a higher LPI is indicative of higher biodiversity

Bibliography

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Fotherqill, Alastair, et al. Planet Earth: As You’ve Never Seen It Before. U of California P, 2006.

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